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JesseKoz

Unknown Cambrian Fossil - Central Australia

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JesseKoz

Location:
The previous weekend I went out for a trip through the West MacDonnell Ranges, west of Alice Springs, NT, Australia. Along the way I stopped at a few locations and examined the rocks near the road for any signs of interesting fossils or minerals. Finally, at the location marked in figure 1.2 below I found some interesting shale / limestone formations that contained fossil, this image displays the locality of the fossils below. Figure 1.1 comes from 'Northern Territory Geological Survey, A Guide to the Geology and Landforms of Central Australia by R B Thompson, 1995, Pg. 103'  and details the stratigraphic layers that run along the West MacDonnell ranges. The location of the fossils I am looking to identify was 30km east of the formations shown in figure 1.1. Figure 1.3 gives a rough estimate of how figure 1.1 and figure 1.2 relate to each other. 

 

From following the clear ridge of Arumbera Sandstone we can see that the ridge just north of the fossil locality is the Arumbera Sandstone. This means the finds are most likely from the Hugh River Shale or the Jay Creek Limestone. The unit age of the Hugh River Shale is listed as 535 - 505 Ma. These strata are part of the Amadeus Basin.

 

Fossil:

I'm unsure if the image below is a fossil created from a living organism or simply a geological feature. The small tube like structures on one surface of the rock are about 0.2-1mm in diameter and range from 1mm - 1cm in length, these can be seen on images 1-4, 1-5, 1-6 and 1-7. It can be hard to make out but the tube structures appear to be bunched into three long rectangular bands, this is best seen in images 1-5 and 1-6. The opposing surface of the rock has banded formations that line up with the groupings of tube structures, seen running vertical in image 1-1 and horizontal in 1-3. A curled lip of finely layered rock can also be seen on the same surface as the tube structures.

 

[EDIT]
From some further reading possibly Anabaritid?

https://www.researchgate.net/publication/228488202_The_tube_wall_of_Cambrian_anabaritids

Kouchinsky, A. and Bengtson, S. 2002. The Tube Wall of Cambrian Anabaritids

 

All image, including more finds from the same location can be seen in the One Drive link below. These could possibly shed more insight.

https://1drv.ms/f/s!Ai3mV0Fc5mW7g90DyT9ZE47yaQhvQw

 

For a better perspective of the area you can check my Google Maps which has the exact location bookmarked as "Unknown Fossil Locality 1".

https://drive.google.com/open?id=17sjqvyah6GekBT8y1cUCLwsgRHj300xb

 

Fig 1.1 (Left), Fig 1.2 (Right)

EOMtDJ5.jpg

Fig 1.3

dxgOITp.jpg

 

1-1

Hugh_River_Shale_Fossil_1-1.jpg

 

1-2

Hugh_River_Shale_Fossil_1-2.jpg

 

1-3

Hugh_River_Shale_Fossil_1-3.jpg

 

1-4

Hugh_River_Shale_Fossil_1-4.jpg

 

1-5

Hugh_River_Shale_Fossil_1-5.jpg

 

1-6

Hugh_River_Shale_Fossil_1-6.jpg

 

1-7

Hugh_River_Shale_Fossil_1-7.jpg

Edited by JesseKoz

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JesseKoz

Using a 40x25mm magnifying glass I'm able to just make out that the tubes are made of tiny segments, each band is very thin. This could possibly be growth lamellae as mentioned in the article below. The tubes also gradually widen, flaring out, possible sign of the flanges mentioned. I cannot identify any tubes that fork, each appearing as a separate column.

 

https://www.researchgate.net/publication/228488202_The_tube_wall_of_Cambrian_anabaritids

Kouchinsky, A. and Bengtson, S. 2002. The Tube Wall of Cambrian Anabaritids

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The Amateur Paleontologist

I love how you're conducting that research :) Sounds really interesting!

Hope you manage to uncover more details about that specimen :)

-Christian

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JesseKoz

@The Amateur Paleontologist Thanks for the reply. I'm really enjoying the process of investigating some of my finds from the weekend.

 

I've attached some photos of other finds from the same location to give an idea of the fossil assemblage. A single Gastropod/Cephalopod shell? (2-3) and fossils of possibly Stromatolites/Microbial mats? (3-1, 5-2, 5-3, 6-1, 7-1). All fossils were found loose on the surface. The same fossils could be seen in the formation bed jutting out from the ground and comprised of the same rock. In images 3-1, and 6-1 fine layers can be seen leading me to believe they are sections of Stromatolite. 5-2 and 5-3 display tiny ring structures that appear to resemble the diameter of the tubes in the initial fossil discussed. Due to the fact all of these finds are heavily worn, image 5-2 and 5-3 could have contained the tube structures that have since worn down.

 

2-3

Hugh_River_Shale_Fossil_2-3.jpg

 

3-1

Hugh_River_Shale_Fossil_3-1.jpg

 

5-2

Hugh_River_Shale_Fossil_5-2.jpg

 

5-3

Hugh_River_Shale_Fossil_5-3.jpg

 

6-1

Hugh_River_Shale_Fossil_6-1.jpg

 

7-1

Hugh_River_Shale_Fossil_7-1.jpg

Edited by JesseKoz

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